NCERT Class 11-Biology: Chapter – 13 Photosynthesis in Higher Plants Part 3 (For CBSE, ICSE, IAS, NET, NRA 2023)

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Question 4:

a. NADP reductase enzyme is located on ________.

b. Breakdown of proton gradient leads to release of ________.


(a) Outer side of thylakoid membrane (Grana-lamella)

(b) ATP molecules

Question 5:

Can girdling experiments be done in monocots? If yes, How? If no, why not?


The monocots cannot carry out girdling experiments. The monocot stem is scattered over all of the width of the trunk by vascular bundles. So, we can՚t reach a particular band of girdling phloem՚s.

Question 6:

Analyse the above reaction and answer the following questions:

a. How many molecules of ATP & NADPH are required to fix one molecule of ?

b. Where in the chloroplast does this process occur?


(a) 3 molecules of ATP are required for phosphorylation and 2 molecules of NADPH are required for reduction of carbon dioxide.

(b) This reaction occurs in the stroma of chloroplast.

Question 7:

Does moonlight support photosynthesis? Find out.


Moonlight does not have enough energy to excite chlorophyll molecules. Hence, moonlight cannot support photosynthesis.

Question 8:

Some of these terms/chemicals are associated with the cycle. Explain.

a. Hatch slack pathway

b. Calvin cycle

c. PEP carboxylase

d. Bundle sheath cells


(a) In plants the process is called the Hatch & Slack Pathway, the glucose synthesis process. M D Hatch and C R Slack discovered it in 1977.

(b) Steps leading to the formation of carbohydrate following the division of the water molecule. This happens in a cyclical manner and is called Calvin Cycle. This was first discovered by Melvin Calvin and his co-workers.

(c) PEP carboxylase is an enzyme. It is present in mesophyll cells of plants. It fixes carbon to form oxaloacetate.

(d) The specialized sclerenchyma cells present around vascular bundles in the veins of plants are called bundle sheath cells.

Question 9:

Where is NADP reductase enzyme located in the chloroplast? What is the role of this enzyme in proton gradient development?


NADP reductase enzyme is located on the outer side of thylakoid membrane. It facilitates breakdown of proton gradient to release energy, i.e.. NADPH.

Question 10:

ATPase enzyme consists of two parts. What are those parts? How are they arranged in the thylakoid membrane? Conformational change occur in which part of the enzyme?


Two parts of the enzyme are ATPase: the head of and the head of . The F0 head is towards the thylakoid՚s inner side while is towards the thylakoid՚s outer side. In part of the enzyme, the conformation changes.

Question 11:

Which products formed during the light reaction of photosynthesis are used to drive the dark reaction?



Question 12:

What is the basis for designating and pathways of photosynthesis?


Carbon is fixed to a carbon compound in case of pathways, i.e.. . In pathways, on the other hand, carbon, i.e.. oxaloacetic acid, is fixed in a four-carbon compound. Thus, number of carbon atoms in the end product is the basis for designating and pathways of photosynthesis.

Short Answer Type Questions

Question 1:

Succulents are known to keep their stomata closed during the day to check transpiration. How do they meet their photosynthetic requirements?


Succulent seedlings are known to keep their stomata closed for transpiration during the day. This prevents carbon dioxide from entering throughout the day. These plants have designed a special approach for ensuring the daily supply of carbon dioxide. These plants fix carbon dioxide at night in the form of malic acid.